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EMMC / SD learning notes
2022-04-23 13:07:00 【MyeDy】
eMMC Partition management 、 Bus protocol and working mode
JDEDC EMMC Agreement Chinese
SD Card agreement Chinese 2.0 3.0
EMMC4.4 Not Boot Mode read process
- wait for 74 A clock
- CMD0 Reset emmc to idle state
Command index | type | Parameters | The reply | abbreviation | Command specification |
---|---|---|---|---|---|
CMD0 | bc | 00000000 | - | GO_IDLE_STATE | Reset the device to idle state |
CMD0 | bc | f0f0f0f0 | - | GO_PRE_IDLE_STATE | Reset the device to pre-idle state |
CMD0 | - | fffffffa | - | GO_INITIATION | Start the replacement boot operation |
- send out CMD1 obtain OCR
Command index | type | Parameters | The reply | abbreviation | Command specification |
---|---|---|---|---|---|
CMD1 | bc | [31:0] OCR | R3 | SEND_OP_COND | request idle Status sent by the device at CMD Send its line OCR structure |
- CMD2 obtain CID
Command index | type | Parameters | The reply | abbreviation | Command specification |
---|---|---|---|---|---|
CMD2 | bc | [31:0] Fill bit | R2 | ALL_SEND_CID | Request device at CMD Send its line CID Number |
- CMD3 Distribute RCA
Command index | type | Parameters | The reply | abbreviation | Command specification |
---|---|---|---|---|---|
CMD3 | ac | [31:16] RCA [15:0] Fill bit | R1 | SET_RELATIVE_ADDR | Assign a relative address to the device |
- CMD9 obtain CSD
Command index | type | Parameters | The reply | abbreviation | Command specification |
---|---|---|---|---|---|
CMD9 | ac | [31:16] RCA [15:0] Fill bit | R2 | SEND_CSD | SEND_CSD The addressed device is CMD Send its equipment specific data online (CSD) |
- CMD7 Set up transfer state
Command index | type | Parameters | The reply | abbreviation | Command specification |
---|---|---|---|---|---|
CMD7 | ac | [31:16] RCA [15:0] Fill bit | R2 | SELECT/DESELECT_C ARD | stay stand-by and transfer Between states or program- ming and disconnect Command to switch devices between States . In both cases , The device is selected with its own relative address and deselected with other addresses ; Address 0 Deselect all devices . |
- CMD13 Get device status
Command index | type | Parameters | The reply | abbreviation | Command specification |
---|---|---|---|---|---|
CMD13 | ac | [31:16] RCA [15:0] Fill bit | R1 | SEND_STATUS | The addressed device sends its status register |
- according to ECSD switch Different bit widths .( Optional ) CMD8, CMD13, CMD6
- CMD18 Reading data
Command index | type | Parameters | The reply | abbreviation | Command specification |
---|---|---|---|---|---|
CMD18 | adtc | [31:0] Data address 1 | R1 | READ_MULTIPLE_ BLOCK | Continuous transmission of data blocks from the device to the host , Until interrupted by the stop command , The number of blocks or required for transmission . |
SD1.0 Initialization flow
- wait for 74 A clock
- CMD0 Reset SD Card to idle state
- CMD8 send out SD Card interface conditions , Contains the voltage information supported by the host , And ask if the card supports . The reserved bit should be set to 0.
Command index | type | Parameters | The reply | abbreviation | Command specification |
---|---|---|---|---|---|
CMD8 | bcr | [31:12] Keep a ,[11:8]VHS,[7:0] Check mode | R7 | SEND_IF_COND | send out SD Card interface conditions , Contains the voltage information supported by the host , And ask if the card supports . The reserved bit should be set to 0. |
- ACMD41 Send card support information (HCS). send out ACMD Need to send first CMD55.
Command index | type | Parameters | The reply | abbreviation | Command specification |
---|---|---|---|---|---|
CMD55 | ac | [31:16]RCA [15:0] Fill bit | R1 | APP_CMD | Tell card , The next command is an application specific command , Instead of standard commands . |
Command index | type | Parameters | The reply | abbreviation | Command specification |
---|---|---|---|---|---|
ACMD41 | bcr | [31] Keep a [30]HCS(OCR30) [29:24] Keep a [23:0]VddVdd voltage (OCR[23:0]) | R3 | SD_SEND_OP_COND | Send card support information (HCS), And ask the cartoon to return through the command line OCR Register contents . When the card is received SEND_IF_COND when ,HCS It works . The reserved bit is set to 0.CCS Bit correspondence OCR[30] |
- Next SD Card initialization is CMD2 and CMD3, Roughly the same as MMC The card process is the same . There are some commands behind SD and MMC It's different , such as switch Your orders are different ,SD The card uses ACMD6 To define the width of the data, and so on , and MMC It's using CMD8 Come on switch.
Command index | type | Parameters | The reply | abbreviation | Command specification |
---|---|---|---|---|---|
ACMD6 | ac | [31:2] Fill bit [1:0] Bus width | R1 | SET_BUS_WIDTH | Define the width of the data bus (‘00’=1bit,‘10’=4bit). The accepted data bus is defined in SCR In the register . |
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